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50 lines
945 B
Go
50 lines
945 B
Go
package random
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import (
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"math/rand"
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"strings"
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"sync"
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"time"
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)
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var r *rand.Rand
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var mu sync.Mutex
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func init() {
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r = rand.New(rand.NewSource(time.Now().UnixNano()))
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}
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// String returns a random string, 20 characters long.
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func String() string {
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mu.Lock()
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defer mu.Unlock()
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var output strings.Builder
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chars := "abcdedfghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
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for i := 0; i < 20; i++ {
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random := r.Intn(len(chars))
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output.WriteString(string(chars[random]))
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}
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return output.String()
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}
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// Float64 returns a random float64 between 0 and 1.
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func Float64() float64 {
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mu.Lock()
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defer mu.Unlock()
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return r.Float64()
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}
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// Intn returns a random int >=0 and < n.
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func Intn(n int) int {
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mu.Lock()
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defer mu.Unlock()
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return r.Intn(n)
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}
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// Jitter returns a randomly-chosen duration between d and 2d.
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func Jitter(d time.Duration) time.Duration {
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mu.Lock()
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defer mu.Unlock()
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return d + time.Duration(r.Float64()*float64(d))
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}
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